He gave away 9 (20 x (3/7) =9) so 21-9=12
Solution:
As given Square L M NO is dilated by a scale factor of two about the center of the square to create square L'M'N'O'.
Original line of Dilation = Along P Q
New Dilated line = P'Q'
As scale factor > 1
1. Image Size > Pre image size
2. The two images will be similar.
3. Length of Dilated Line P' Q' = 2 × Length of PQ
As you can see from the diagram drawn below, Dilated line P'Q' will contain the point P and Q.
All four points P,Q,Q',P' are collinear , lie in the same line.
Option (2) dilated line P'Q' will contain the points P and Q is true.
The product of 4xy and y² + 2x can also be written as
4xy(y² + 2x)
When we have brackets like this, we multiply whatever is left of the brackets by everything inside.
1) 4xy multiplied by y²
4xy x y² = 4xy³
2) 4xy multiplied by 2x
4xy x 2x = 8x²y
3) Add together 4xy³ and 8x²y
4xy³ + 8x²y